Soon this system of healing came to be called "Perkinsism," as a tribute to the inventor. The popularity of the system spread rapidly in the United States, particularly in New England, every city and many towns patronizing Perkins' practitioners and healers. From this country the craze spread to Great Britain, and even to the Continent. Centers of treatment, and even hospitals, were established by the "Perkinsites," and the fame of the tractors increased daily in ever widening circles. In Europe alone it is reported that over 1,500,000 cures were performed, and the medical fraternity were at their wit's ends to explain the phenomenon. Finally, Dr. Haygarth, of London, conceived the idea that the real virtue of the cures was vested in the minds, belief and imagination of the patients rather than in the tractors, and that the cures were the result of the induced mental states of the patients instead of by the metallic qualities of the apparatus. He determined to investigate the matter under this hypothesis, and accordingly constructed a pair of tractors of wood, painted to resemble the genuine ones. The following account by Bostock describes the result: "He accordingly formed pieces of wood into the shape of tractors and with much assumed pomp and ceremony applied them to a number of sick persons who had been previously prepared to expect something extraordinary. The effects were found to be astonishing. Obstinate pains in the limbs were suddenly cured; joints that had long been immovable were restored to motion, and, in short, except the renewal of lost parts or the change in mechanical structure, nothing seemed beyond their power to accomplish." The exposure of this experiment, and the general acceptance of the explanation of the phenomena, caused "Perkinsism" to die out rapidly, and at the present time it is heard of only in connection with the history of medicine and in the pages of works devoted to the subject of the effect of the mind over the body.